A novel low-loss integrated 60 GHz cavity filter with source-load coupling using surface micromachining technology

This paper presents a novel surface micromachined low-loss integrated cavity filter with a pair of transmission zeros using a simple source-load coupling scheme for emerging 60 GHz applications. The proposed method eliminates the dielectric loss by elevating the cavity-based filter into the air with the aid of the polymer-core conductor surface micromachining technology. The electrical fields of the cavity are thus entirely in air. A coplanar waveguide input and output interface is designed for easy integration with other planar electronics. The inter-cavity inductive coupling is realized through the use of pillar array iris, with the source-load capacitive coupling achieved with integrated coplanar waveguide lines. This combination of couplings creates a pair of transmission zeros to help achieve better selectivity. A measured insertion losses as low as 1.92 dB, along with a pair of transmission zeros, has been observed at 60 GHz.